Quaternary data-storage materials and the preparation method thereof

ABSTRACT

An organic compound has the following chemical structure: 
                         
wherein R is different from R*; R and R* are independently hydrogen,
 
                         
halogen, nitro or methoxyl; and R1 is a C1-C6 alkyl or a phenyl group. A quaternary data storage device includes a bottom electrode, a top electrode, and the organic film layer sandwiched between the bottom electrode and the top electrode.

The present invention claims priority to Chinese Patent Application No.20110444853.0, filed on Dec. 27, 2011.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an organic compound, a quaternary datastorage device containing the organic compound, and a method ofpreparing the organic compound and the quaternary data storage device.

2. Discussion of the Related Art

At the end of 2009, the movie Avatar with the 3D Imax technique won awide reputation around the globe due to the unprecedented enjoyment itbrought visually and acoustically. However, the film of this movieweighs up to 700 kilograms, indicating that the current memory materialsand techniques are far behind the pace of the rapid development of theinformation society. Till now, almost all the efforts in the highdensity data storage field are focused on increasing the data storagedensity via diminishing the scale of the memory cells. When inorganicmaterial suffered its bottleneck due to its intrinsic properties tofurther diminish the scale, researchers have turned their attention topolymeric and organic materials possessing good processability with theanticipation that the data storage density could be further enhanced bydiminishing the scale of the memory units. The scale can only bediminished from the microscale to nanoscale with the storage densityincrease no more than 1000 times, which also cannot meet therequirements for super-high density data storage in the long run. Thereason is that current optical, magnetic and electric memories based onpolymeric and organic materials are generally conventional binary memory(“0” and “1”). To further enhance the data storage density, researcherssuccessively achieved ternary storage (“0”, “1”, “2”) with inorganicnanowires and organic materials respectively, breaking through theconventional binary memory, dramatically increasing the storage densityof unit area tens of thousands of times (i.e., for the same 40 storageunits, the storage density for ternary memory is more than 10 milliontimes higher than that for binary memory). See, e.g., H. Li, Q. Xu, N.Li, R. Sun, J. Ge, J. Lu, H. Gu, F. Yan, J. Am. Chem. Soc. 2010, 132,5542; and Y. W. Jung, S. H. Lee, A. T. Jennings, R. Agarwal, Nano Lett.2008, 8, 2056. In this way, enormous storage capacity can be attainedwith less storage units, making the storage cells more compact. And thefabricating process for the device can be simplified, thus achieving anew generation of super-high density data storage devices with highcapacity, small dimension, low power consumption and low cost.

The data storage density can be further enhanced with continuingincrease in the quantity of electrically stable states. Accordingly,there exists a need for new data storage materials with increasedquantity of electrically stable states and data storage density.

SUMMARY OF THE INVENTION

In one embodiment of the present invention, an organic compound has thefollowing chemical structure:

wherein R is different from R*; R and R* are independently hydrogen,

halogen, nitro or methoxyl; and R1 is a C1-C6 alkyl or a phenyl group.

In another embodiment of the present invention the organic compound isselected from the group consisting of

In another embodiment of the present invention, a quaternary datastorage device includes a bottom electrode, a top electrode, and anorganic film layer sandwiched between the bottom electrode and the topelectrode. The organic film layer contains the organic compound.

In another embodiment of the present invention, the thickness of thebottom electrode is 10-300 nm, the thickness of the top electrode is20-300 nm, and the thickness of the organic layer is 20-150 nm.

In another embodiment of the present invention, the bottom electrode isselected from the group consisting of indium-tin oxide (ITO), anevaporatable metal, and a conductive polymer. The evaporatable metal canbe gold, platinum, silver, aluminum, or copper; and the conductivepolymer can be polythiophene or polyaniline.

In another embodiment of the present invention, the top electrode isselected from the group consisting of an evaporatable metal and a metaloxide. The evaporatable metal can be gold, platinum, silver, or copper;and the metal oxide can be indium-tin oxide (ITO).

In another embodiment of the present invention, a method of preparing aquaternary data storage device includes depositing an organic film layeron a bottom electrode, the organic film layer containing the organiccompound, and depositing a top electrode to form a bottomelectrode/organic film layer/top electrode sandwich structure.

In another embodiment of the present invention, a method of preparingthe organic compound includes the following steps:

(1) reacting 4,4′-sulfonyldianiline with maleic anhydride to obtain acompound of the following chemical structure:

(2) converting the compound of step (1) to a diazonium salt of thefollowing chemical structure:

(3) reacting the diazonium salt of step (2) with

to obtain a compound of the following chemical structure:

(4) converting the compound of step (3) to a compound of the followingchemical structure:

(5) converting the compound of step (4) to a diazonium salt of thefollowing chemical structure:

(6) reacting the diazonium salt of step (5) with

to obtain the organic compound of the following chemical structure:

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 shows a schematic graph of a quaternary data storage device witha sandwich structure.

FIG. 2 shows the current-voltage characteristics of the quaternary datastorage device.

FIG. 3 shows the current stability of the quaternary data storage deviceunder a constant stress.

FIG. 4 shows quaternary data storage performance of the data storagedevice.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, example of which is illustrated in the accompanying drawings.

The inventors reported the preparation of an organic molecule of thefollowing formula:

and the fabrication of a data storage device containing this organicmolecule. See, H. Li, Q. Xu, N. Li, R. Sun, J. Ge, J. Lu, H. Gu, F. Yan,J. Am. Chem. Soc. 2010, 132, 5542. This memory device has ternarydata-storage performance under an external applied voltage.

After further extensive research, the inventors surprisingly found thata data storage device containing an organic compound of the followingstructure has an unexpected quaternary data-storage performance under anexternal applied voltage:

wherein R is different from R*; R and R* are independently hydrogen,

halogen, nitro or methoxyl; and R1 is a C1-C6 alkyl or a phenyl group.

The organic compound can be selected from the group consisting of

This organic compound can be prepared by a method including thefollowing steps:

(1) reacting 4,4′-sulfonyldianiline with maleic anhydride to obtain acompound of the following chemical structure:

(2) converting the compound of step (1) to a diazonium salt of thefollowing chemical structure:

(3) reacting the diazonium salt of step (2) with

to obtain a compound of the following chemical structure:

(4) converting the compound of step (3) to a compound of the followingchemical structure:

(5) converting the compound of step (4) to a diazonium salt of thefollowing chemical structure:

(6) reacting the diazonium salt of step (5) with

to obtain the organic compound of the following chemical structure:

The data storage device containing the organic compound of the chemicalstructure

can be prepared in accordance with the method described in H. Li, Q. Xu,N. Li, R. Sun, J. Ge, J. Lu, H. Gu, F. Yan, J. Am. Chem. Soc. 2010, 132,5542, which is hereby incorporated by reference in its entirety.

Specifically, the data storage device includes a bottom electrode, anelectro-active layer, and a top electrode.

The bottom electrode can be selected from indium-tin oxide (ITO), anevaporatable metal, and a conductive polymers. The evaporatable metalcan be gold, platinum, silver, aluminum, or copper; and the conductivepolymer can be polythiophene or polyaniline.

The electro-active layer includes the organic compound of the chemicalstructure:

The top electrode is selected from the evaporatable metal and some metaloxides. The evaporatable metal can be gold, platinum, silver, or copper;and the metal oxide can be indium-tin oxide (ITO).

The thickness of the bottom electrode can be 10-300 nm, the thickness ofthe top electrode can be 20-300 nm, and the thickness of the organiclayer can be 20-150 nm.

The active material was first deposited onto the bottom electrode andthen the top electrode was deposited onto the organic layer through ashadow mask to construct a bottom electrode/active layer/top electrodesandwich configuration.

The memory performance of the as-fabricated device was then evaluated.

EXPERIMENTAL EXAMPLES Example 1 The Synthesis of AsymmetricDiazosulfonylbenzene Compounds

General Structure:

For R1=methyl, R2=butyl, the synthetic processes are shown below:

(1) 4,4′-sulfonyldianiline (1.24 g˜4.96 g) and maleic anhydride (0.49g˜1.96 g) were dissolved in acetone (40-60 mL), and after stirring for4-12 h a lot of white precipitate formed. After filtration, the solidwas washed by cool acetone to give white solid (compound 1).

(2) Then icy aqueous solution of sodium nitrite was added drop wise intothe mixture of compound 1, DMF and 6-12 mol L⁻¹ concentratedhydrochloric acid (or sulfuric acid (98%, w %) or fluoroboric acid (40%,w %)) in an ice bath under stirring. The mixture was filtered afterstirring for 0.5-2 h at 0-5° C. and the obtained diazonium salt solutionwas stored in an ice bath.

(3) N,N-dimethylaniline was dissolved in DMF (0.5-2 mol L⁻¹) and thenadded dropwise into the solution of diazonium salt below 10° C. Thereaction proceeded for 0.5-2 h, and thereafter the pH value was adjustedto 5-7. The mixture was stirred for another 3-5 h and then poured into alarge quantity of water to precipitate solid. After filtration the solidwas dried and recrystallized to obtain compound 2.

(4) Compound 2 (1 g) was dissolved in methanol and concentratedhydrochloric acid (40-60 mL) was then added followed by refluxing for1-3 h. Afterward the mixture was poured into a large quantity of waterto precipitate solid. After filtration the solid was dried and compound3 could be obtained through column chromatography.

(5) Then icy aqueous solution of sodium nitrite was added dropwise intothe mixture of compound 3, DMF and concentrated hydrochloric acid (orsulfuric acid or fluoroboric acid at a certain concentration) in an icebath under stirring. The mixture was filtered after the solutionstirring for 0.5-2 h at 0-5° C. and the obtained diazonium salt solutionwas stored in an ice bath.

(6) N,N-dibutylaniline was dissolved in DMF (0.5-2 mol L⁻¹) and was thenadded dropwise into the solution of diazonium salt below 10° C. Thereaction proceeded for 0.5-2 h, and thereafter the pH value was adjustedto 5-7. The mixture was stirred for another 3-5 h and then poured into alarge quantity of water to precipitate solid. After filtration the solidwas dried and recrystallized to give target molecule A1:

Anal. Calcd for C₃₄H₄₀N₆O₂S: C, 68.43; H, 6.76; N, 14.08. Found: C,68.47; H, 6.72; N, 14.13. ¹H-NMR (DMSO-d₆): δ (ppm)=8.09 (d, 4H), 7.91(d, 4H), 7.79 (d, 4H), 6.82 (d, 4H), 3.39 (t, 4H), 3.07 (s, 6H),1.59-1.47 (m, 4H), 1.40-1.30 (m, 4H), 0.91 (t, 6H).

When R1 and R2 are replaced by methyl, ethyl, propyl, butyl, pentyl orhexyl, the reaction processes are similar and the ratios of thereactants are the same. What is different is the N,N-dimethylaniline instep 3 and N,N-dibutylaniline in step 6, which are replaced byN,N-diethylaniline, N,N-dipropylaniline, N,N-dibutylaniline,N,N-dipentylaniline or N,N-dihexylaniline. The obtained target compoundsare A2, A3, A4, A5, A6, A7, A8, A9, A10, A11, A12, A13, A14 and A15,respectively. And their molecular structure, element analysis and ¹H-NMRresults are shown below:

Anal. Calcd for C₃₀H₃₂N₆O₂S: C, 66.64; H, 5.97; N, 15.54. Found: C,66.67; H, 6.02; N, 15.51. ¹H-NMR (DMSO-d₆): δ (ppm)=8.08 (d, 4H), 7.90(d, 4H), 7.78 (d, 4H), 6.81 (d, 4H), 3.54-3.21 (m, 4H), 3.10 (s, 6H),1.12 (t, 6H).

Anal. Calcd for C₃₂H₃₆N₆O₂S: C, 67.58; H, 6.38; N, 14.78. Found: C,67.55, H, 6.39, N, 14.75. ¹H-NMR (DMSO-d₆): δ (ppm)=8.11 (d, 4H), 7.91(d, 4H), 7.81 (d, 4H), 6.83 (d, 4H), 3.89 (t, 4H), 3.08 (s, 6H),1.75-1.58 (m, 4H), 0.89 (t, 6H).

Anal. Calcd for C₃₆H₄₄N₆O₂S: C, 69.20; H, 7.10; N, 13.45. Found: C,69.18, H, 7.11, N, 13.47. ¹H-NMR (DMSO-d₆): δ (ppm)=8.08 (d, 4H), 7.89(d, 4H), 7.80 (d, 4H), 6.84 (d, 4H), 3.81 (t, 4H), 3.03 (s, 6H),1.64-1.49 (m, 4H), 1.38-1.27 (m, 8H), 0.95 (t, 6H).

Anal. Calcd for C₃₈H₄₈N₆O₂S: C, 69.91; H, 7.41; N, 12.87. Found: C,69.94, H, 7.44, N, 12.90. ¹H-NMR (DMSO-d₆): δ (ppm)=8.08 (d, 4H), 7.90(d, 4H), 7.78 (d, 4H), 6.83 (d, 4H), 3.79 (t, 4H), 3.05 (s, 6H),1.58-1.46 (m, 4H), 1.31-1.29 (m, 12H), 0.91 (t, 6H).

Anal. Calcd for C₃₄H₄₀N₆O₂S: C, 68.43; H, 6.76; N, 14.08. Found: C,68.45; H, 6.73; N, 14.06. ¹H-NMR (DMSO-d₆): δ (ppm)=8.09 (d, 4H), 7.91(d, 4H), 7.80 (d, 4H), 6.83 (d, 4H), 3.83 (t, 4H), 3.43 (m, 4H), 1.59(m, 4H), 1.17 (t, 6H), 0.93 (t, 6H).

Anal. Calcd for C₃₆H₄₄N₆O₂S: C, 69.20; H, 7.10; N, 13.45. Found: C,69.23; H, 7.11; N, 13.47. ¹H-NMR (DMSO-d₆): δ (ppm)=8.06 (d, 4H), 7.91(d, 4H), 7.79 (d, 4H), 6.82 (d, 4H), 3.74 (t, 4H), 3.45-3.33 (m, 4H),1.49-1.40 (m, 4H), 1.35-1.26 (m, 4H), 1.13 (t, 6H), 0.87 (t, 6H).

Anal. Calcd for C₃₈H₄₈N₆O₂S: C, 69.91; H, 7.41; N, 12.87. Found: C,69.93; H, 7.43; N, 12.91. ¹H-NMR (DMSO-d₆): δ (ppm)=8.07 (d, 4H), 7.92(d, 4H), 7.80 (d, 4H), 6.83 (d, 4H), 3.77 (t, 4H), 3.49-3.42 (m, 4H),1.61-1.52 (m, 4H), 1.38-1.29 (m, 8H), 1.17 (t, 6H), 0.93 (t, 6H).

Anal. Calcd for C₄₀H₅₂N₆O₂S: C, 70.55; H, 7.70; N, 12.34. Found: C,70.57; H, 7.68; N, 12.36. ¹H-NMR (DMSO-d₆): δ (ppm)=8.12 (d, 4H), 7.93(d, 4H), 7.80 (d, 4H), 6.85 (d, 4H), 3.79 (t, 4H), 3.45-3.36 (m, 4H),1.50-1.44 (m, 4H), 1.28-1.20 (m, 12H), 1.13 (t, 6H), 0.94 (t, 6H).

Anal. Calcd for C₃₈H₄₈N₆O₂S: C, 69.91; H, 7.41; N, 12.87. Found: C,69.93; H, 7.44; N, 12.89. ¹H-NMR (DMSO-d₆): δ (ppm)=8.07 (d, 4H), 7.89(d, 4H), 7.82 (d, 4H), 6.83 (d, 4H), 3.75 (t, 8H), 1.64-1.57 (m, 4H),1.53-1.46 (m, 4H), 1.33-1.28 (m, 4H), 1.01 (t, 12H).

Anal. Calcd for C₄₀H₅₂N₆O₂S: C, 70.55; H, 7.70; N, 12.34. Found: C,70.57; H, 7.75; N, 12.33. ¹H-NMR (DMSO-d₆): δ (ppm)=8.10 (d, 4H), 7.92(d, 4H), 7.81 (d, 4H), 6.84 (d, 4H), 3.75 (t, 8H), 1.66-1.61 (m, 4H),1.55-1.49 (m, 4H), 1.37-1.32 (m, 4H), 1.30-1.26 (m, 4H), 1.04 (t, 12H).

Anal. Calcd for C₄₂H₅₆N₆O₂S: C, 71.15; H, 7.96; N, 11.85. Found: C,71.18; H, 7.93; N, 11.88. ¹H-NMR (DMSO-d₆): δ (ppm)=8.10 (d, 4H), 7.93(d, 4H), 7.79 (d, 4H), 6.84 (d, 4H), 3.77 (t, 8H), 1.63-1.58 (m, 4H),1.56-1.51 (m, 4H), 1.36-1.32 (m, 4H), 1.29-1.25 (m, 8H), 0.89 (t, 12H).

Anal. Calcd for C₄₂H₅₆N₆O₂S: C, 71.15; H, 7.96; N, 11.85. Found: C,71.12; H, 7.97; N, 11.84. ¹H-NMR (DMSO-d₆): δ (ppm)=8.11 (d, 4H), 7.93(d, 4H), 7.82 (d, 4H), 6.85 (d, 4H), 3.76 (t, 8H), 1.53-1.48 (m, 8H),1.32-1.27 (m, 12H), 0.97 (t, 12H).

Anal. Calcd for C₄₄H₆₀N₆O₂S: C, 71.70; H, 8.21; N, 11.40. Found: C,71.69; H, 8.22; N, 11.37. ¹H-NMR (DMSO-d₆): δ (ppm)=8.07 (d, 4H), 7.88(d, 4H), 7.78 (d, 4H), 6.81 (d, 4H), 3.71 (t, 8H), 1.50-1.44 (m, 8H),1.29-1.20 (m, 16H), 0.87 (t, 12H).

Anal. Calcd for C₄₆H₆₄N₆O₂S: C, 72.21; H, 8.43; N, 10.98. Found: C,72.24; H, 8.44; N, 10.97. ¹H-NMR (DMSO-d₆): δ (ppm)=8.09 (d, 4H), 7.90(d, 4H), 7.81 (d, 4H), 6.83 (d, 4H), 3.72 (t, 8H), 1.51-1.45 (m, 8H),1.29-1.20 (m, 20H), 0.92 (t, 12H).

Example 2

Compound A1 was selected as the electroactive material sandwichedbetween the top and bottom electrode to construct the memory device.Before deposition of the organic layer, the ITO glass was precleaned byultrasonication with water, acetone, and 2-propanol, each for 5-30 min.Compound A1 (20-30 mg) was placed in quartz crucible and was then movedinto the molybdenum boat. The evaporation of the organic material wasn'tlaunched until the pressure inside was lower than 3×10⁻³ Pa. Thethickness of the organic layer was controlled between 60 and 100 nm bythe film thickness monitor. After the successful deposition of theorganic layer, a porous metal mask (pore radius=0.1 mm) was fixed ontothe organic film. Thereafter aluminum hanging on the tungsten filamentswas evaporated onto the film when the pressure inside was lower than8×10⁻³ Pa to form top electrodes. The scheme of the device is shown inFIG. 2.

FIG. 3 shows the current-voltage curve of the as-fabricated device. Whena bias from 0 to −4 V was applied to a cell in the device, three abruptincrease of the current through the device was observed around −1.14 V,−2.60 V and −3.38 V respectively, suggesting that there are fourdistinct current states (OFF, ON1, ON2 and ON3) for the measured cell(sweep1 in FIG. 2). In order to demonstrate that these observed fourstates were all stable and this phenomenon was not by coincidence, weselected another cell to perform the reproducibility and stability test.In the beginning, a constant voltage of −1 V was added to evaluate thestability of the OFF state, and the corresponding I-t curve was denotedas line A in FIG. 3. A short period of only 600 s was tested due to thelimit of the data storage capability of the instrument. And no obviousdegradation of the OFF current was observed. Then a subsequent sweepfrom 0 to −1.7 V was applied to the cell, similar to the first cell, anabrupt increase in current was observed around −1.2 V, indicating thetransition from the OFF state to the ON1 state (sweep3 in FIG. 2).Afterward the stability of the ON1 state was tested with a constantvoltage of −1 V (line B in FIG. 3). Then the voltage was swept from 0 to−3V, and a transition from ON1 to ON2 state was observed around −2.55 V.Thereafter the stability of the ON2 state was tested with a constantvoltage of −1 V (line C in FIG. 3). Lastly the voltage was swept from 0to −4V, and a transition from ON2 to ON3 state was observed around −3.2V. Then the stability of the ON3 state was tested with a constantvoltage of −1 V (line D in FIG. 3). The reproducibility and stability ofthe four distinct states were further confirmed by measurement of othercells in the device. The OFF, ON1, ON2 and ON3 states of the device canbe encoded as “0”, “1”, “2” and “3” generally adopted in data storage.And further 32 cells were selected to be programmed to different stateswith different on-switching voltages and then a constant voltage of −1 Vwas applied to read the current level. FIG. 4 was obtained viacombination of two states, which demonstrates the feasibility for theapplication of quaternary data storage. The programmed states cannot bereprogrammed to the OFF state, suggesting the WORM-type data-storagebehavior.

In this invention, the bottom electrode is not confined to theindium-tin oxide (ITO) glass. Various evaporatable metals includinggold, platinum, silver, aluminum and copper and conductive polymersincluding polythiophene and polyaniline are also involved. And the topelectrode is not limited to aluminum. Evaporatable metals includinggold, platinum, aluminum and copper and metal oxide like indium-tinoxide (ITO) are involved.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. An organic compound of the following chemicalstructure:

wherein R is different from R*; R and R* are independently hydrogen,

halogen, nitro or methoxyl; and R1 is a C1-C6 alkyl or a phenyl group.2. The organic compound of claim 1, wherein the organic compound isselected from the group consisting of


3. A quaternary data storage device comprising: a bottom electrode, atop electrode, and an organic film layer sandwiched between the bottomelectrode and the top electrode, the organic film layer including theorganic compound of claim
 1. 4. The quaternary data storage device ofclaim 3, wherein the thickness of the bottom electrode is 10-300 nm, thethickness of the top electrode is 20-300 nm, and the thickness of theorganic layer is 20-150 nm.
 5. The quaternary data storage device ofclaim 3, wherein the bottom electrode is selected from the groupconsisting of indium-tin oxide (ITO), an evaporatable metal, and aconductive polymer.
 6. The quaternary data storage device of claim 5,wherein the evaporatable metal is gold, platinum, silver, aluminum, orcopper; and the conductive polymer is polythiophene or polyaniline. 7.The quaternary data storage device of claim 3, wherein the top electrodeis selected from the group consisting of an evaporatable metal and ametal oxide.
 8. The quaternary data storage device of claim 7, whereinthe evaporatable metal is gold, platinum, silver, or copper; and themetal oxide is indium-tin oxide (ITO).
 9. A method of preparing aquaternary data storage device comprising depositing an organic filmlayer on a bottom electrode, the organic film layer including theorganic compound of claim 1, and depositing a top electrode to form abottom electrode/organic film layer/top electrode sandwich structure.10. The method of claim 9, wherein the thickness of the bottom electrodeis 10-300 nm, the thickness of the top electrode is 20-300 nm, and thethickness of the organic layer is 20-150 nm.
 11. The method of claim 9,wherein the bottom electrode is selected from the group consisting ofindium-tin oxide (ITO), an evaporatable metal, and a conductive polymer.12. The method of claim 11, wherein the evaporatable metal is gold,platinum, silver, aluminum, or copper; and the conductive polymer ispolythiophene or polyaniline.
 13. The method of claim 9, wherein the topelectrode is selected from the group consisting of an evaporatable metaland a metal oxide.
 14. The method of claim 13, wherein the evaporatablemetal is gold, platinum, silver, or copper; and the metal oxide isindium-tin oxide (ITO).
 15. A method of preparing an organic compound ofthe following chemical structure:

comprising the following steps: (1) reacting 4,4′-sulfonyldianiline withmaleic anhydride to obtain a compound of the following chemicalstructure:

(2) converting the compound of step (1) to a diazonium salt of thefollowing chemical structure:

(3) reacting the diazonium salt of step (2) with

to obtain a compound of the following chemical structure:

(4) converting the compound of step (3) to a compound of the followingchemical structure:

(5) converting the compound of step (4) to a diazonium salt of thefollowing chemical structure:

(6) reacting the diazonium salt of step (5) with

to obtain the organic compound of the following chemical structure

wherein R is different from R*; R and R* are independently hydrogen,

halogen, nitro or methoxyl; and R1 is a C1-C6 alkyl or a phenyl group.16. The organic compound prepared according to claim 15 is selected fromthe group consisting of